1. Field of the Invention
The present invention relates to positioning mechanisms, and in particular to positioning mechanisms for adjustably holding equipments at the desired angular, translational and rotational positions with respect to a mounting support.
2. Prior Art
It is well known for use as equipment support stands to employ a combination of an upright, extending upwardly from a floor base, with a boom mounted to the upright by means of a an adjustable support mechanism, which mechanism allows positioning and holding in position a variety of equipments of the types that may require a variety of large and small position adjustments. The needs for these adjustments may occur frequently and randomly. Such an adjustable apparatus is particularly useful in conjunction with the type of equipment which often requires critical placement, but which also requires adjustment through experimentation, such as microphones, lights, cameras, lamps, gauges, medical instruments and the like.
A variety of stands and positioning mechanisms are presently known and in use for adjustably positioning items carried by such mechanism. However, existing positioning mechanisms are frequently complicated and cumbersome. Such devices all employ some variation of a boom arm carried on an upright, the boom arm being angularly positionable as well as longitudinally positionable with respect to the stand. To fix or lock the boom arm in any desired longitudinal or angular position, various types of locking mechanisms are employed. Regardless of the particular type of locking mechanism used, the prior art devices generally employ multiple separate locking mechanisms, one for the purpose of locking the boom arm against angular movement, and one to lock the boom against translational and rotational movement. As a consequence, the user often has to manipulate at least two separate locking mechanisms to position the equipment at the desired location. The use of the separate locking mechanisms means that the user must deal with them individually at each adjustment.
The existing stands are generally adequate for their intended uses, but there is a need for a mechanism which can position and hold a boom at a wide variety of angles relative to the upright column, allow the extension of the boom outward from the upright column, and allow for rotation of the boom to orient (to aim, for example), the equipment being held, and then to securely hold the boom at any selected angle.
In general, the prior art devices use friction to hold the boom in the desired position. If the prior art locking mechanism is the type having a variable force capability, the friction adjustment may be either loosened, allowing movement of the boom against the frictional force, or increased, effectively preventing the movement of the boom in any direction.
Most of the prior art devices do not aim to achieve, and are not designed to allow for, a controllable application of friction. While it is possible to accomplish some degree of gradual adjustment of the prior art mechanisms by using the method of loosening the prior art friction adjustment, this method is makeshift, at best, because the prior art mechanism is not readily adjustable to a precise force, and the resistance to movement is therefore neither predictable nor finely adjustable.
A need exists therefore for a positioning mechanism having a simple construction which allows precise and repeatable adjustment of the amount of applied friction, in order to allow adjustment of the boom in all three directions of movement: angular, rotational and translational.